Helicopter engines should normally be operated below certain predetermined levels of temperature, output torque, and engine speed, and for convenience, the critical limits for these factors will be called the "over-stress" limits. If a helicoptor engine is operated above these limits, its life may be drastically shortened, and expensive overhaul of the engine may be required. If these engine limits are exceeded for long periods of time, the engine may fail, with possibly drastic consequences. Helicopter pilots normally operate the engine well below these over-stress limits. However, when a pilot's attention is concentrated on his work, such as lifting a load with a sling, or operating into or out of tight quarters, his attention is normally required away from the cockpit instrumentation, and it is quite possible that engine limits may be inadvertently exceeded under this type of condition.
It is an important object of the present invention to provide a warning and alternatively a control system especially designed for helicopters.
It is noted in passing that turbine engine warning and control systems have been proposed heretofore for conventional turbine aircraft; however, these prior systems were not suitable for or applicable to the special conditions presented in helicopter operations.